A008874 3x+1 sequence starting at 63.

63, 190, 95, 286, 143, 430, 215, 646, 323, 970, 485, 1456, 728, 364, 182, 91, 274, 137, 412, 206, 103, 310, 155, 466, 233, 700, 350, 175, 526, 263, 790, 395, 1186, 593, 1780, 890, 445, 1336, 668, 334, 167, 502, 251, 754, 377, 1132, 566, 283, 850, 425, 1276, 638, 319, 958, 479, 1438, 719, 2158, 1079

Offset

0,1

Comments

a(n) = A008875(n - 2) for n > 1.

Doesn't reach a power of 2 until a(103) = 16. - Alonso del Arte, May 18 2015

References

Richard K. Guy, Unsolved Problems in Number Theory, E16.

Links

T. D. Noe, Table of n, a(n) for n=0..107

Index entries for sequences related to 3x+1 (or Collatz) problem

Maple

f := proc(n) option remember; if n = 0 then 63; elif f(n-1) mod 2 = 0 then f(n-1)/2 else 3*f(n-1)+1; fi; end;

Mathematica

NestList[If[EvenQ[#], #/2, 3# + 1] &, 63, 100] (* Vincenzo Librandi, Jul 29 2014 *)

Prog

(Haskell)
a008874 n = a008874_list !! n
a008874_list = 63 : iterate a006370 63
-- Reinhard Zumkeller, Aug 30 2012
(Magma) [n eq 1 select 63 else IsOdd(Self(n-1)) select 3*Self(n-1)+1 else Self(n-1) div 2: n in [1..70]]; // Vincenzo Librandi, Jul 29 2014

Crossrefs

Cf. A006370.

Row 63 of A347270.

Sequence in context: A098140 A008895 A359563 * A045112 A255568 A143033

Adjacent sequences: A008871 A008872 A008873 * A008875 A008876 A008877

Keyword

nonn,easy

Author

N. J. A. Sloane.

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), Apr 27 2001

Status

approved